Background Sequences - The spacecraft is operating nominally in performing
the beta-supplement daily recording and transmission of science data. The
mm142 sequence executed successfully from 01-144 (5/24/01) through 01-146
(5/26/01). The mm143 sequence has performed well since it started on 01-147
(5/27/01). It terminates on 01-150 (5/30/01). The mm144 sequence,
successfully uplinked on 01-149 (5/29/01), begins executing on 01-151
(5/31/01).

Other - Nine more Roll Only Targeted Observations (ROTOs) were performed
since the last report. MGS has completed a total of 107 ROTOs to date.

Spacecraft Health:

All subsystems report good health and status.

The Sun Monitor Ephemeris fault protection continues to be disabled to
prevent another C-Mode entry while the Spacecraft Team investigates the root
cause of the failure. Other fault protection routines will continue to
protect MGS from losing its attitude knowledge.

Uplinks:

There have been 17 uplinks to the spacecraft during the past week, including
new star catalogs and ephemeris files, instrument command loads, the
background sequences cited above, and ROTO mini-sequence mz103.

Three solar array position management scripts were updated to offset the
commanded solar array positions by 35 degrees instead of the previous offset
of 25 degrees. The update should extend the life of the Partial Shunt
Assemblies by reducing the amount of excess power generated by the solar
arrays

There have been 5,406 command files radiated to the spacecraft since launch.

Upcoming Events:

DOY 01-172 (6/21/01) marks the end of the beta-supplement phase and the
beginning of the nominal mapping phase of the mission. Planetary and orbital
geometry will allow the HGA to auto-track the Earth without impacting the
HGA boom. Nominal mapping sequences will not be as command intensive as the
beta-supplement sequences. Therefore, 28-day background sequences will be
the norm instead of the 3 and 4 day beta-supplement sequences.

Another MGS Mars Relay On-orbit UHF Test will be conducted with Stanford
University between 01-177 (6/26/01) and 01-180 (6/29/01).